Fix: chooseMultivariate(variantMap) ignore empty array members

Author: panhongx

improveai/src/main/java/ai/improve/DecisionContext.java

@@ -107,7 +107,7 @@ public <T> T random(List<T> variants) {
     }
 
     /**
-     * @see ai.improve.DecisionModel#optimize(Map)
+     * @see ai.improve.DecisionModel#chooseMultivariate(Map)
      */
     public Decision<Map<String, ?>> chooseMultivariate(Map<String, ?> variants) {
         if(variants == null || variants.size() <= 0) {
@@ -119,11 +119,17 @@ public <T> T random(List<T> variants) {
         List<List> categories = new ArrayList();
         for(Map.Entry<String, ?> entry : variants.entrySet()) {
             if(entry.getValue() instanceof List) {
-                categories.add((List)entry.getValue());
+                if(((List)entry.getValue()).size() > 0) {
+                    categories.add((List) entry.getValue());
+                    allKeys.add(entry.getKey());
+                }
             } else {
                 categories.add(Arrays.asList(entry.getValue()));
+                allKeys.add(entry.getKey());
             }
-            allKeys.add(entry.getKey());
+        }
+        if(categories.size() <= 0) {
+            throw new IllegalArgumentException("valueMap values are all empty list!");
         }
 
         List<Map<String, ?>> combinations = new ArrayList();

improveai/src/main/java/ai/improve/DecisionModel.java

@@ -337,16 +337,19 @@ public <T> Decision<T> chooseFrom(List<T> variants, List<Double> scores) {
      *      {"style":"italic", "size":5},
      * ])
      * @param variants Variants can be any JSON encodeable data structure of arbitrary complexity
-     *                 like chooseFrom(). The value of the dictionary is expected to be a List.
-     *                 If not, it would be treated as an one-element List anyway. So
-     *                 optimize({"style":["bold", "italic"], "size":3}) is equivalent to
-     *                 optimize({"style":["bold", "italic"], "size":[3]})
+     *                 like chooseFrom(). The value of the dictionary is expected to be a list.
+     *                 If not, it would be automatically wrapped as a list containing a single item.
+     *                 So chooseMultivariate({"style":["bold", "italic"], "size":3}) is equivalent to
+     *                 chooseMultivariate({"style":["bold", "italic"], "size":[3]})
      * @return An IMPDecision object.
-     * */
+     */
     public Decision<Map<String, ?>> chooseMultivariate(Map<String, ?> variants) {
         return given(null).chooseMultivariate(variants);
     }
 
+    /**
+     * A shorthand of chooseMultivariate(variantMap).get().
+     */
     public Map<String, ?> optimize(Map<String, ?> variants) {
         return given(null).optimize(variants);
     }

improveai/src/test/java/ai/improve/DecisionModelTest.java

@@ -716,6 +716,32 @@ public void testOptimize() {
         assertNotNull(theme.get("size"));
     }
 
+    @Test
+    public void testOptimize_empty_member() {
+        Map variants = new HashMap();
+        variants.put("font", Arrays.asList("Italic", "Bold"));
+        variants.put("size", Arrays.asList(12, 13));
+        variants.put("color", new ArrayList<String>());
+        DecisionModel decisionModel = new DecisionModel("theme");
+        Map<String, String> theme = decisionModel.optimize(variants);
+        assertEquals(2, theme.size());
+        assertNotNull(theme.get("font"));
+        assertNotNull(theme.get("size"));
+    }
+
+    @Test
+    public void testOptimize_all_empty() {
+        Map variants = new HashMap();
+        variants.put("color", new ArrayList<String>());
+        DecisionModel decisionModel = new DecisionModel("theme");
+        try {
+            decisionModel.optimize(variants);
+            fail(DefaultFailMessage);
+        } catch (IllegalArgumentException e) {
+            e.printStackTrace();
+        }
+    }
+
     @Test
     public void testWhichVariadic() {
         DecisionModel decisionModel = new DecisionModel("theme");